Hi, Sorry if this is a basic question, I have little experience of RMAN backups I'm afraid.
I'm having some problems with my RMAN backups.
The RMAN script and backup process was setup by the person who originally installed the DB.
It is supposed to do an incremental backup daily at 12:05 am and 12:05 pm and a full backup every three days

The backups get consistently get larger over time, often being much larger than my datafiles. Even with very little done ~100Mb is added each day (see table below).

If a full backup is being run every 3 days then why are the incremental backups being kept and things keep getting larger and larger overtime? Surely every 3 days the incremental backups should be reset and the backup folders reach a steady state size?

If a full backup is being run every 3 days then why are the incremental backups being kept and things keep getting larger and larger overtime? Surely every 3 days the incremental should reset and the backup folder stay in asteady state size?
Also why aren't backups being deleted every 7 days?

I can see why you are questioning what is occuring. This is very difficult to figure out and would suggest you get a calendar out and try to track it. Maybe visualizing it will help you understand.

A couple of comments:

1) A "FULL BACKUP" is not part of an incremental strategy. It has to be an incremental level 0 (which is automatically done if one does not exist).

2) RMAN retention policy specifies which backups must be retained to meet your data recovery requirements (which is very different than backup dates).

So take for example if you truly do "FULL BACKUP"s every 3 days. You must maintain 4 copies to be able to recover 7 days ago.

July 1 - FULL backup
July 4 - FULL backup
July 7 - FULL backup (What if you need to recover to July 2 (5 days ago) which backup can you use? <b>July 1</b>
July 10 - FULL backup (What if you need to recover to July 3 (7 days ago) which backup can you use? <b>July 1</b>
July 13 - FULL BACKUP (What if you need to recover to July 6 (7 days ago) which backup can you use? <b>July 4</b> <i>only now can you delete July 1st backup</i> So you have to keep 4 full backups.

Now that is separate from your incremental backups. I am very interested in how this is working. Generally speaking when using incremental strategies in the manner shown in your backup script you should be using a RETENTION POLICY of 1. So my question is how do you know your retention policy is 7? I don't have any way to test this...and of course it would take me more than a week but here is a guess.

Now this may be wrong....because I do not know if you truly have RETENTION POLICY OF 7 days if this is what is occuring. Because if the RETENTION POLICY OF 7 Days "overrides" the RECOVER COPY ... UNTIL command then you will have 3 more days at least of incremental backups before deletions start occuring. You will need to look at your log files to figure that one out.

This makes thing clearer for me (I think!). I really appreciate you taking the time to respond with that level of detail.
I believe the retention policy is 7 as a show all in RMAN returns:-
CONFIGURE RETENTION POLICY TO RECOVERY WINDOW OF 7 DAYS;

If I follow what you are saying then I would expect backups to be kept for at least 11 days before they start to auto delete as obsolete (7 + 4).
If I change the retention policy to 1 then this would drop to 4 days (possibly 5 days as 4+1).
Interestingly my backup sizes since the 13th July (11 days since the oldest available backup!) have dropped to ~350Mb per day - from a peak on nearly 4Gb. This is the size i would expect.

What I still don't understand is why backups beyond 11 days are still being kept. Currently as of today 16th July, the oldest available backup is the 2nd July (I've check with report obsolete and its not obsolete).

That's 3 days longer than I would expect if I understand correctly. Any idea why?

LKBrwn_DBA - thank you for you suggestion, although from what I can see this syntax / method is what Oracle suggests for RMAN. How would I delete the incremental backups to the copy?